1. Field of the Invention
The present invention relates generally to vascular access devices and more specifically to subcutaneously implanted catheter ports.
2. Background Information
A variety of implantable devices, known as subcutaneous ports, are utilized to administer therapies that require central venous access through a non-coring needle received by the port, obviating the need for transdermal central venous catheters. For applications such as bodily fluid exchange and/or removal therapies, drug delivery, pheresis, hemofiltration, hemodialysis and other applications that must be periodically repeated, subcutaneous ports are preferable to other methods of accessing a patient's vascular system, such as direct percutaneous introduction of a needle through the patient's skin into a blood vessel or use of transcutaneous catheters.
A variety of subcutaneous ports have been previously described. A subcutaneous port has one or more reservoirs, each covered by a needle-penetrable, self-sealing septum. The reservoir opens up to a stem which connects to a catheter. Current ports 100, an example of which is shown in FIG. 3, have a small round outlet hole 106 exiting the side of the reservoir 102 and a stem 104 defining an outlet extending from that hole 106. All the edges and corners resulting from the outlet 106 create dead-zones, where blood and other fluids traversing the port 100 may stagnate. Acute edges and surfaces that confer abrupt directional changes in the fluid flow through the internal regions of the port lead to dead-zones, cell shearing, platelet activation and clotting.
The buildup of blood or fluid is known as sludge, and limits the ability of the port to provide fluid flow in and out of the port, reducing the effectiveness, safety and overall useful life of the port. If the port is used to transfuse blood, blood trapped in these dead spaces has the tendency to form clots and block the flow of fluid through the reservoir. An additional limitation of existing designs is that the edges and corners of current designs also prevent the passage of wires through the port to clear a blockage.
Accordingly, there has been a need for an improved implantable, subcutaneous single or multi-port vascular access device for bodily fluid exchange therapies and other drug delivery applications, which include specific geometries exhibiting, for example, increased port patency, reduced dead-flow zones, and increased mixing within the port. Additionally, there has been a need for vascular access devices that are inexpensive, more comfortable, longer lasting, and easier to locate within the patient's body and suitable for both low and high volume transfer of fluids.